1. Technical Field
The present invention relates to the field of video telephony and, more particularly, to a video telecommunications server for providing fast forward and fast reverse, for example, for video message review or Internet video screening.
2. Description of the Related Arts
The American Telephone and Telegraph Company, now commonly known as AT&T, introduced a PicturePhone (R) video telephone in the 1960's. An approximately one megahertz bandwidth analog television signal was generated by a small camera of special video telephone apparatus for transmission over standard telephone wire facilities to a special wideband switch which communicated with other such switches. It was expected that both caller and calling party would be equipped with such special video telephone apparatus. Calls were to be placed in a conventional manner from one PicturePhone video telephone apparatus to another where the received television signal was displayed on a relatively small screen (compared to that of a television set).
With the advent of the so-called World Wide Web and the advancement of digital telephony, AT&T and other industry participants have joined in promoting standards for video telephony including International Telecommunications Union (ITU) standards H.320 and H.324. Within the H.320 standard is a video portion for ISDN (relatively high speed) digital data rates, namely standard H.261, while another standard, H.263, has been promulgated for slower speed, plain old telephone service (POTS) data rates. One viewing the POTS video telephony call will see a relatively choppy, slow frame rate, picture sequence evolve. Both the H.261 and H.263standards (hereinafter referred to as the H.26x standards) provide for some digital video signal compression. In this manner, a relatively high resolution signal can be provided over a relatively narrow bandwidth telecommunications channel. Typical digital data rates for POTS are 28.8 kilobits per second; while ISDN rates exceed one megabit per second.
Other video compression standards are known, for example, the well known Moving Pictures Experts Group (MPEG) video compression standards. A key difference between the H.26x standards of the ITU and those of MPEG is that in an MPEG system for broadcast, intra frames are generally sent regularly and reasonably often so that synchronization and recovery of individual frame data is relatively easy in MPEG. In an H.26x compressed signal, intra frames are generally sent infrequently, for example, because of the one-to-one, two way communication between video phone callers. A receiver requests that the transmitter send an intra frame, whenever there is a loss of synch, for example, due to a loss of transmission.
In MPEG compression and decompression, one can assume that intra frames providing information for decompressing a following sequence of compressed data frames will be present at regular intervals in the received data bitstream and so information can be extracted from those frames to form a fast forward bitstream, for example, for a digital video tape recorder. An article entitled "Fast Scan Technology for Digital Video Tape Recorders" of Boyce et al. published in IEEE Transactions on Consumer Electronics, August, 1993, at pages 186-191, describes the implementation of fast forward and fast reverse in an MPEG environment and, in particular, in connection with the design of an Hitachi high definition digital video tape recorder (DVTR). Patents describing related DVTR technology include U.S. Pat. Nos. 5,377,051; 5,576,902; 5,583,650; and 5,592,299.
Audio messaging is well known and provided presently as a network service offering, as a stand-alone product for home or office or associated with a private branch exchange. So-called voicemail involves typically an announcement that the called party is presently unavailable, an announcement that one may leave a message after a signal and the recording of the message. Fast scanning of a message in either a forward or backward direction serves little useful purpose as a user could not understand the message--it would be unintelligible. On the other hand, from the use of video cassette recorders, users are well acquainted with the advantages of fast forward and reverse of video sequences. The user is able to move to a scene of particular interest and then, using appropriate input commands, typically by remote control keypad, slow the video and audio to normal speed to obtain both intelligible audio and video.
As video telephony applications advance, it is perceived that there will exist a need for video messaging or other video telecommunications review opportunities where a user may wish to fast scan through a video telecommunication in either a forward or reverse direction without intelligible audio, for example, to locate a point in the video telecommunication at which the user wishes to proceed with playing the video telecommunication at a normal rate with intelligible audio. In other words, there exists a need in the art for a video telecommunications server that may be associated, for example, with a telecommunications switch or Internet server for permitting fast scanning of video telecommunications upon user request.